Navigation apparatus, navigation method, and navigation program

ABSTRACT

Navigation apparatus, methods, and programs merge and correct a plurality of types of past traffic information. The apparatus, methods, and programs may store a plurality of types of past traffic information, each type of past traffic information having a priority and may merge the stored past traffic information in accordance the priorities. The apparatus, methods, and programs may detect adjacency relationships among the plurality of links; and, if a detected link number indicates that the corresponding link is not adjacent to adjacent links, replaces the detected link number for the link, the replaced link number indicating that the link is adjacent to the adjacent links.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Applications No. 2004-126955 filed onApr. 22, 2004 and No. 2004-126962 filed on Apr. 22, 2004 including thespecifications, drawings and abstracts are incorporated herein byreference in their entirety.

BACKGROUND

1. Related Technical Fields

Related fields include a navigation apparatus and a navigation method.

2. Description of Related Art

In a conventional navigation system, for example, traffic informationsuch as traffic congestion information is received from a road trafficinformation communication system and stored. The stored information isused for searching for a shortest route (refer to, for example, JapaneseUnexamined Patent Application Publication No. 2002-148067).

SUMMARY

According to the aforementioned navigation system, traffic informationdata received from the road traffic information communication system isonly for limited roads. Without storing accurate traffic informationdata relevant to every road, the navigation apparatus is less likely toidentify the most suitable route.

In general, various kinds of useful traffic information data exist otherthan traffic information data from the road traffic informationcommunication system. For example, travel history data from a probe car(hereinafter referred to as probe data) and road traffic sensor censusdata are available.

In order to accurate traffic information data relevant to every road, itis beneficial to provide a navigation system and a navigation method toobtain various kinds of traffic information data in accordance withestablished data precision priorities.

Various exemplary implementations provide a navigation apparatus,including a controller. The controller may store a plurality of types ofpast traffic information, each type of past traffic information having apriority and may merge the stored past traffic information in accordancethe priorities.

Various exemplary implementations provide a navigation method. Themethod may include the steps of storing a plurality of types of pasttraffic information, each type of past traffic information having apriority and merging the stored past traffic information in accordancethe priorities.

Various exemplary implementations provide a navigation program. Theprogram may include instructions for storing a plurality of types ofpast traffic information, each type of past traffic information having apriority and instructions for merging the stored past trafficinformation in accordance the priorities.

Various exemplary implementations provide a navigation apparatus thatcorrects traffic information data, the traffic information dataincluding travel history data for a plurality of links, the apparatuscomprising a controller. The controller may detect adjacencyrelationships among the plurality of links; and, if a detected linknumber indicates that the corresponding link is not adjacent to adjacentlinks, replaces the detected link number for the link, the replaced linknumber indicating that the link is adjacent to the adjacent links.

Various exemplary implementations provide a navigation method forcorrecting traffic information data, the traffic information dataincluding travel history data for a plurality of links. The method mayinclude the steps of detecting adjacency relationships among theplurality of links; and replacing, if a detected link number indicatesthat the corresponding link is not adjacent to adjacent links, thedetected link number for the link, the replaced link number indicatingthat the link is adjacent to the adjacent links.

Various exemplary implementations provide a navigation program forcorrecting traffic information data, the traffic information dataincluding travel history data for a plurality of links. The program mayinclude instructions for detecting adjacency relationships among theplurality of links; and instructions for replacing, if a detected linknumber indicates that the corresponding link is not adjacent to adjacentlinks, the detected link number for the link, the replaced link numberindicating that the link is adjacent to the adjacent links.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary implementations will now be described with reference to theaccompanying drawings, wherein:

FIG. 1 is a block diagram showing a navigation apparatus according to anexemplary implementation of the principles described herein;

FIG. 2 is a flowchart showing a method of transmitting search dataaccording to an exemplary implementation of the principles describedherein;

FIG. 3 is a detailed flowchart showing a method of setting priorityaccording to an exemplary implementation of the principles describedherein;

FIG. 4 is a detailed flowchart showing a method of merging dataaccording to an exemplary implementation of the principles describedherein;

FIG. 5 is a block diagram showing a navigation apparatus according to aaccording to another exemplary implementation of the principlesdescribed herein;

FIG. 6 is a flowchart showing a method of transmitting search dataaccording to another exemplary implementation of the principlesdescribed herein;

FIG. 7 is a flowchart showing a method of storing corrected travelhistory data according to an exemplary implementation of the principlesdescribed herein;

FIG. 8 is a flowchart showing a method of correcting travel history dataaccording to an exemplary implementation of the principles describedherein;

FIGS. 9(a) and 9(b) are diagrams showing a correction of travel timesand link numbers;

FIGS. 10(a) and (b) are diagrams showing a correction of travel timesand link numbers;

FIGS. 11(a) and (b) are diagrams showing a correction of travel timesand link numbers; and

FIGS. 12(a) and (b) are diagrams showing a correction of travel timesand link numbers.

DETAILED DESCRIPTION OF EXEMPLARY IMPLEMENTATIONS

FIG. 1 is a diagram showing an exemplary vehicle navigation system. Thevehicle navigation system 10 may include, for example, a currentposition detection unit 11, and/or a GPS receiver that receives radiowaves sent from an artificial satellite of a satellite navigation system(also known as GPS) and detects a current position of the vehicle aswell as a present day and time.

In addition, the navigation system 10 may include, for example, an inputunit 12 such as, for example, a portable remote controller, theoperation of which may send required information through transmissionto, for example, a receiving section (not shown) of a controller 13(described later). Note that instead of, or in addition to, using theabove remote controller as the input unit 12, a touch panel may beprovided on a display screen, for example, in a liquid crystal displaypanel of an output unit 16 (described later).

Furthermore, the navigation system 10 may include, for example, thecontroller 13, a memory 14, a communication unit 15, and/or the outputunit 16. The controller 13 may include, for example, a CPU, a RAM, a ROMand/or the receiving sections described above interconnected via, forexample, bus lines.

The controller 13 may provide route guidance of the vehicle and displaymaps based upon, for example, detection output of the current positiondetection unit 11, operation of the input unit 12, information stored inthe memory 14, output of the communication unit 15, and/or output of anexclusive information communication system 20 (described later).

The memory 14 may include, for example, a hard disk. For example, mapdata and/or traffic information data may be stored in the memory 14 inthe form of, for example, a database that is readable by the controller13. The communication unit 15 may receive, for example, road trafficinformation from the exclusive information communication system 20 andmay output the data to the controller 13.

The exclusive information communication system 20, for example,installed in an exclusive information center, may execute wirelesscommunication with, for example, the communication unit 15, a roadtraffic information communication system installed in a road trafficinformation center (hereinafter also referred to as VICS® 30), and/orthe probe car 40.

Furthermore, the exclusive information communication system 20 mayinclude, for example, a controller 21, a communication unit 22, and/or amemory 23. The controller 21 may transmit search data, for exampleaccording to one or more of the exemplary methods shown in FIGS. 2-4.For example, the controller 21 may communicate with the communicationunit 15, VICS 30, and/or the probe car 40 via the communication unit 22.Note that instructions for implementing one or more of the exemplarymethods shown in FIGS. 2-4 may be written in advance, for example, on aROM of the controller 21.

Accumulated probe data, VICS data, road traffic census data, road widthinterpolation data, and/or link travel times based on such each data maybe stored in a the memory 23, for example, as statistical data in theform of a database.

The output unit 16 may include, for example, a display device. Basedupon control by the controller 13, the output unit 16 may displayinformation required for the vehicle. Note that the output unit 13 maybe installed in an instrument panel on an anterior wall of the vehicleand may display information on a display panel such as a liquid crystalpanel.

As described above, the controller 21 may transmit search data accordingto the exemplary method shown in FIG. 2. FIG. 2 shows an exemplarymethod of transmitting search data. As shown in FIG. 2, operation of themethod begins in step 100 where a target area is set. For example, mapdata stored in the memory 14 may be divided into one or more targetareas defined by predetermined regions, such as, for example, prefectualregions.

Next, in step 200, a time period is set. For example, stored data may bemerged in accordance with priorities of the stored data (describedlater) so the time period is set based on the priorities. The timeperiod may be set, for example, on a 24-hour basis.

In step 300, a priority is set. The priority may be set, for example,according to the exemplary priority setting method shown in FIG. 3.Then, in step 400, the search data is merged. The search data may bemerged, for example, according to the exemplary method of merging datashown in FIG. 4. In step 500, the search data is transmitted. Forexample, the communication unit 22 may send the merged search data asdata necessary for searching for a route to the controller 13 via thecommunication unit 15 and the data may be stored in the database of thememory 14. Operation of the method ends.

As described above, the controller 21 may set priority data according tothe exemplary method shown in FIG. 3. FIG. 3 shows an exemplary methodof setting priority. As shown in FIG. 3, in step 310, accumulated datais obtained. For example, data at a current time for each target area(for example, set in step 100) may be obtained from a database of thememory 23, and may include, for example, accumulated probe data, VICSdata, and/or road traffic census data.

Next, in step 320, current data is obtained. For example, thecommunication unit 22 may receive current probe data corresponding tothe current time from the probe car 40 and provide it to the controller21. The communication unit 22 may also receive current VICS data fromthe VICS 30 and provide it to the controller 21.

In step 330, current data is set. For example, data including, forexample, current probe data obtained in step 320 and/or current VICSdata for links whose data are not included in the current probe data maybe set as current data.

As used herein, the term “link” refers to, for example, a road orportion of a road. For example, according to one type of road data, eachroad may consist of a plurality of componential units called links. Eachlink may be separated and defined by, for example, an intersection, anintersection having more than three roads, a curve, and/or a point atwhich the road type changes.

Next in step 340, for each link that exists in both the current probedata and current VICS data, a time difference may be calculated betweenthe link travel time according to accumulated probe data and the linktravel time according to the current data set in step 330. After eachtime difference for each link is calculated, the average value of thecalculated time differences (hereinafter referred to as average timedifference) may be further calculated for each target area (set in step100). In a similar manner, for example, an average time differencebetween accumulated VICS data and the current data, and average timedifference between road traffic census data and the current data may becalculated.

In step 350, priority is set. For example, based on the average timedifferences in step 340, priorities for accumulated road traffic censusdata, VICS data, and probe data may be established.

For example, according to the current time, if the average timedifference of road traffic census data, the average time difference ofVICS data, and the average time difference of probe data are ranked indescending order according to the of amount of average time difference,the priorities may be established according to that order. According tothis example, assume a priority variable n=1 for road traffic censusdata, n=2 for accumulated VICS data, and n=3 for stored probe data.

As described above, the controller 21 may merge data according to theexemplary method shown in FIG. 4. FIG. 4 shows an exemplary method ofmerging data. As shown in FIG. 4, in step 410, accumulated navigationdata is initialized. For example, road width interpolation data at adesired time (for example, eight o'clock) for a target area may be readout from a database of the memory 14.

As used herein, “road width interpolation data” is data that representsan estimated time required to travel a link. The time required to travelthe link is estimated based on the type of road the link represents(e.g., local road, expressway, etc.) and may be adjusted based on thewidth of the road the link represents (e.g., two lanes, 4 lanes, etc.).Thus, according to this example, road width interpolation data at thedesired time of eight o'clock would indicate, that based on the width ofthe road, it will take 11 minutes to travel the link at eight o'clock.

Then, in step 420, variable n is set as 1. In step 430, data whosepriority N is equal to the n may be extracted from the accumulated data.For example, among accumulated road traffic census data corresponding ton=1 for the target area, only data at the target time (for example,eight o'clock) may be read out from the memory 14.

Next, in step 431, the read out data is merged. According to thisexample, road width interpolation data read out in step 410 may beoverwritten with road traffic census data read out in step 430. If, forexample, a link includes no road traffic census data but only road widthinterpolation data, the road width interpolation data may be used forthat link.

In step 432, it is determined whether n=N. N denotes a total number oftypes of data prioritized, for example, in step 350. In this example,N=3 because there are three types of prioritized data: road trafficcensus data, accumulated VICS data, and stored probe data. If n≠N, thenoperation continues to step 433. If n=N, operation jumps to step 440.

In step 433, the variable n is updated to n=n+1. According to thisexample, n=n+1=2. Thus, when returning to step 430, accumulated VICSdata corresponding to n=2 for the target area, and at the target time(for example, eight o'clock) may be read out from the database of thememory 14.

When returning to step 431, the read out data is merged. According tothis example, accumulated data, which includes the merged road trafficcensus data from the previous step 431, may be overwritten with VICSdata read out in step 430. If a link includes no accumulated VICS databut only accumulated data (which includes merged road traffic censusdata) the road traffic census data may be used for that link.

According to this example, in step 433, the variable n is updated ton=n+1=3. In step 430, accumulated probe data corresponding to n=3 forthe target area and at the target time (for example, eight o'clock) maybe read out from the database of the memory 14.

When returning to step 431, the read out data is merged. For example,accumulated data, which includes merged VICS data and merged trafficcensus data from previous steps 431 may be overwritten with probe dataread out in step 430. If a link includes no accumulated probe data butonly accumulated data, the VICS data may be used for that link.

According to this example, n=N=3 in step 432. It should be appreciatedthat steps 410-433 may be repeated for each target area at each targettime.

In step 440, it is determined whether all data has been merged for alltarget areas set in step 100 and also relevant to each target time in aperiod of time set in step 200. If the data has not been merged for alltarget areas and all target times, operation returns to step 410. If thedata has been merged for all target areas and all target times,operation ends.

According to the above exemplary implementation, a plurality of types ofdata exists, which may include redundant information. An average timedifference between current data and stored data is calculated for eachtype of accumulated data, and a priority is established based on thesize of the difference. Then each type of data is merged with the storedaccumulated data according to the established priority. Because manysources and/or types of data may be preferentially merged, reliabletraffic information may be obtained for a greater number of linkscompared to using just one source of data. Thus, accurate trafficinformation for a larger area may be transmitted for a high-qualityroute search. In addition, priorities are established for eachpredetermined area, so that it is possible to provide applicable searchdatabase in view of regional characteristics.

According to the above exemplary implementation it is possible to searchfor a guidance route based on accumulated data necessary for search inthe database of the memory 14. Therefore, the route may be searchedwithin a wider target area since, due to the merging of many sources ofdata, highly accurate traffic congestion information is available for agreater number of links.

While various features have been described in conjunction with theexamples outlined above, various alternatives, modifications,variations, and/or improvements of those features and/or examples may bepossible. Accordingly, the examples, as set forth above, are intended tobe illustrative. Various changes may be made without departing from thebroad spirit and scope of the underlying principles.

For example, in step 350 priorities may be established for each type ofaccumulated data in advance. In step 330, as described above, whencurrent probe data and current VICS data exist redundantly, currentprobe data is applied for current data. However, current data may becreated by weighting both of current probe data and current VICS dataand averaging both of them.

In step 431 as described above, data is merged by overwritingaccumulated data in a database. However, it is also possible to set eachspecified ratio for each type of stored data in order of the prioritiesand merge data by multiplying each stored data by each specified ratioand averaging the calculation results.

In steps 100 through 400, for example, the navigation system 10 maydirectly obtain the data and execute the same operations in step 100through 400 for the data instead.

Hereinafter, another exemplary implementation of the principlesdiscussed herein will be described. In the first exemplaryimplementation, accumulated probe data, that is, travel history datarecorded by a probe car, is utilized as data for searching for a route.However, such travel history data is not always relevant to all routes.For example, if stored route data does not include travel history datafor the target area, the travel history data may be unreliable. Thus,the unreliable travel history data is not useful for searching for aroute, displaying traffic information, and so on.

In order to resolve such issues as described above, it is beneficial tocorrect travel history data.

FIG. 5 is a diagram showing an exemplary of a vehicle navigation system.The vehicle navigation system 101 may include, for example, a currentposition detection unit 110, and/or a GPS receiver that receives radiowaves sent from an artificial satellite of a satellite navigation system(also known as GPS) and detects a current position of the vehicle aswell as a present day and time.

In addition, the navigation system 101 may include, for example, aninput unit 120 such as, for example, a portable remote controller, theoperation of which may send transmit information to a receiving section(not shown) of the controller 130 (described later). Note that insteadof using the above remote controller as the input unit 120, for example,a touch panel may be provided along a display screen in a liquid crystaldisplay panel of an output unit 160 (described later) may be employed asthe input unit 120.

Furthermore, the navigation system 101 may include, for example, thecontroller 130, a memory 140, a communication unit 150, and/or theoutput unit 160. The controller 130 may include, for example, a CPU, aRAM, and/or a ROM as well as the receiving sections, for example,interconnected via bus lines.

The controller 130 may transmit search data, for example, according tothe exemplary method shown in flowchart in FIG. 6. For example, thecontroller 130 may provide route guidance of the vehicle and displaymaps based upon detection output of the current position detection unit110, operation of the input unit 120, information stored in the memory140, output of the communication unit 150, and/or output of theexclusive information communication system 201 (described later).

The memory 140 may include, for example, a hard disk. For example, mapdata and/or travel history data may be stored in the memory 140, forexample, in the form of a database that is readable by the controller130. Note that such travel history data may include link numbersallocated for links as well as passing times, i.e., times at which thelinks along a vehicle travel route will be passed.

The communication unit 150 may receive road traffic information from theexclusive information communication system 201 and may output it to thecontroller 130. Furthermore, the exclusive information communicationsystem 201 may transfer various kinds of traffic information data whichare received from a road traffic information communication systeminstalled in a road traffic information center (hereinafter alsoreferred to as VICS® 30).

The output unit 160 may include, for example, a display device. Basedupon control by the controller 130, the output unit 160 may displayinformation required for the vehicle. Note that the output unit 160 maybe installed, for example, in an instrument panel on an anterior wall ofthe vehicle and may display on a display panel such as a liquid crystalpanel.

As discussed above, the controller 130 may transmit search data, forexample, according to the exemplary method of transmitting search datashown FIG. 6. As shown in FIG. 6, in step 1100, travel history data isread out. For example, Link numbers allocated for links as well aspassing times at the links along a vehicle travel route may be read outfrom a database of the memory 114. Next, in step 1200, travel historydata is corrected. The travel history data may be corrected, forexample, according to the exemplary method of correcting travel historydata shown in FIGS. 7 and 8.

In step 1300, it is determined whether all of the travel history data iscorrected. If all of the travel history data has not been corrected,operation returns to step 110. If all of the travel history data hasbeen corrected, operation continues to step 1400.

In step 1400, the corrected travel history data is stored. For example,the travel history may be stored in a database of the memory 114. Then,operation of the method ends.

As discussed above, the travel history data may be corrected accordingto the exemplary method shown in FIGS. 7 and 8. As shown in FIGS. 7 and8, in step 1210, a first link number is obtained. For example, a linknumber at the earliest time among travel history data, for example, readout in step 1100 is obtained as the first link number Na.

In step 1220, a second link number is obtained. For example, a linknumber which chronologically appears after the first link number Na isobtained as the second link number Nb among the travel history data.

Then in step 1230, it is determined whether there is a link number thatchronologically appears after the second link number Nb in the travelhistory data. If a link number does not chronologically appear after thesecond link number, operation ends. If a link number chronologicallyappears after the second link number, operation continues to step 1231.In step 1231, the link number that continuously appears after the secondlink number Nb is set as the third link number Nc.

Next, in step 1240, it is determined whether the link corresponding tothe first link number Na (hereinafter referred to as the first link La)is adjacent to the link corresponding to the second link number Nb(hereinafter referred to as the second link Lb). For the purpose of thisexample, an adjacency relationship is detected between the first linkand the second link when both links are connected with each other in mapdata.

If the first link La is adjacent to the second link Lb, operationcontinues to step 1241. If the first link La is not adjacent to thesecond link Lb, operation jumps to step 1250. In step 1241, the firstlink number is reset in step 1241. For example, the second link numberNb may be set as the first link number Na. Then, operation returns tostep 1220, where a new second link number Nb is obtained.

In step 1250, it is determined whether the first link La and the linkcorresponding to the third link number Nc (hereinafter referred to asthe third link Lc) are adjacent in the map data. If the first link Laand the third link Lc are adjacent, operation continues to step 1251. Ifthe first link La and the third link Lc are not adjacent, operationjumps to step 1260.

In step 1251, the second link number Nb is replaced. For example, asshown in FIG. 9(a), the travel history data may include “1”s as thefirst link numbers Na at traveling time 10:00:00 and 10:00:01, “98”s asthe second link numbers Nb at traveling time 10:00:02, 10:00:03, and10:00:04, and “2”s as the third link numbers Nc at traveling time10:00:05 and 10:00:06.

Thus, according to this example, the first link La is not connected withthe second link Lb on map data because the first link number Na is “1”and the second link number Nb is “98.” That is, there is no adjacencyrelationship between the two links. In addition, according to thisexample, the first link La is connected with the third link Lc on mapdata because the first link number Na is “1” and the third link numberNc is “2.” There is an adjacency relationship between the first link Laand the third link Lc.

Thus, for example, in step 1251, the each second link number Nb attravel time 10:00:02 and 10:00:03 would be replaced with the first linknumber Na, that is, “1” as shown in FIG. 9(b). The second link number Nbat 10:00:04 would be replaced with the third link number Nc, that is “2”as shown in FIG. 9(b).

By replacing the second link number in step 1251, even if an incorrectlink number is allocated for a link which has no relationship withadjacent links (previous/following links), it may be corrected with oneor more adjacent link numbers.

Then in step 1252, the first link number is reset. For example, thethird link number Nc may be set as the first link number Na. Operationreturns to step 1220, where a new second link number is obtained.

In step 1260, it is determined whether there is a link that is adjacentwith both of the first link La and the second link Lb in the map data.Hereinafter such an adjacent link is referred to as a common link Lab.

If a common link Lab exists, operation continues to step 1261. If acommon link Lab does not exists, operation jumps to step 1270. In step1261, it is determined whether there is only one travel time includingthe first link number Na. If there is more than one travel timeincluding the first link number Na, operation continues to step 1262. Ifthere is only one travel time including the first link number Na,operation jumps to step 1264.

For example, as shown in FIG. 10(a), travel history data may include“1”s as the first link numbers Na at traveling time 10:00:00, 10:00:01,and 10:00:02, “3”s as the second link numbers Nb at traveling time10:00:03 and 10:00:04, and “4”s as the third link numbers Nc attraveling time 10:00:05 and 10:00:06.

According to this example, the first link number Na is “1” and thesecond link number Nb is “3.” Thus, there is a common link Lab havinglink number “2” in the map data that is adjacent to both the first linkLa and the second link Lb. According to this example, more than onetravel time including the first link number Na exist.

In step 1262, at least part of the first link number Na is replaced.According to this example, the first link number Na at travel time10:00:02 is replaced with the link number allocated for the common linkLab, that is, “2,” as shown in FIG. 10(b). Then, in step 1263, the firstlink number is reset. For example, the second link number Nb is set asthe first link number Na. Operation returns to step 1220.

By replacing at least part of the first link number Na, even if a linknumber is missing, a link number allocated for a common link “Lab” maybe appropriately applied.

In step 1264, one or more link numbers are replaced. For example, asshown in FIG. 11(a), travel history data may include link number “1”s attraveling time 10:00:00 and 10:00:01, “2” at 10:00:02, “3” as the firstlink number Na at 10:00:03, “5”s as the second link numbers Nb at10:00:04 and 10:00:05, and “6” as the third link number Nc at 10:00:06.

According to this example, the first link number Na is “3” and thesecond link number Nb is “5.” Thus, there is a common link Lab includinglink number “4” in the map data which is adjacent to both the first linkLa and the second link Lb. In addition, in the example, only one traveltime including the first link number Na exists.

According to this example, when the link numbers are replaced in step,1264, the link number at travel time 10:00:01 may be replaced with linknumber “2,” as described in FIG. 11(b). Then the link number at traveltime 10:00:02 is replaced with link number “3.” The link number attravel time 10:00:03 is replaced with link number “4.”

By replacing one or more link numbers in step 1264, even if a linknumber is missing, a link number allocated for a link which is adjacentto the missing link may be appropriately used. Then, the first linknumber is reset in step 1265. For example, the second link number Nb isset as the first link number Na, and operation returns to step 1220.

In step 1270, it is determined whether there is a link that is adjacentto both the first link La and the third link Lc in the map data.Hereinafter, such an adjacent link is referred to as a common link Lac.

If a common link Lac exists, operation continues to step 1271. If acommon link Lac does not exist, operation jumps to step 1280.

In step 1271, the second link number Nb is replaced with the common linknumber Lac. For example, as shown in FIG. 12(a), travel history data mayinclude “1”s as the first link numbers Na at traveling times 10:00:00and 10:00:01, “98”s as the second link numbers Nb at traveling times10:00:02 and 10:00:03, and “3”s as the third link numbers Nc attraveling times 10:00:04, 10:00:05, and 10:00:06.

According to this example, the first link number Na is “1” and the thirdlink number Nc is “3.” Thus, it is determined that there is a commonlink Lac including link number “2” that is adjacent to both the firstlink La and the third link Lc. According to this example, in step 1271,the link numbers “98” at travel time 10:00:02 and 10:00:03 would bereplaced with the link number allocated for the common link Lac, thatis, “2” as shown in FIG. 12(b).

By replacing the second number Nb with the common link Lac number, instep 1271, even if an incorrect link number is allocated for a linkwhich has no relationship with adjacent links, it may be accuratelycorrected with a link number for a link adjacent to the link inquestion. In step 1272, the first link number is reset in step 1272. Forexample, the third link number Nc is set as the first link number Na,and operation returns to step 1220.

In step 1280, it is determined whether there is an adjacencyrelationship between the second link Lb and the third link Lc in the mapdata. If the second link Lb is not adjacent to the third link Lc in themap data, operation continues to step 1281. If the second link Lb isadjacent to the third link Lc in the map data, operation jumps to step1282.

In step 1281, the third link number Nc is set as the second link numberNb and a link number that chronologically appears after the replacedsecond link number Nb is set as the third link number Nc among travelhistory data. Then, operation returns to step 1280.

In step 1282, the third link number Nc is set as the first link numberNa and operation returns to step 1220.

As described above, if there is no remaining link number whichcontinuously appears after the second link number Nb, for example, ifthe second link Lb is adjacent to a destination for the travel historydata, operation of the exemplary method ends.

According to the above described exemplary methods shown in FIGS. 6-8,the controller 113 may search for a guidance route based on, for examplea request for display by the input unit 112. During the route search,the controller 113 may, for example, search for a route and/or displaytraffic information, based on the corrected travel history data, forexample, stored in the database of the memory 114. Therefore, after thecorrection, a reliable route may be searched and traffic information maybe correctly displayed with using the dependable travel history data.

While various features have been described in conjunction with theexamples outlined above, various alternatives, modifications,variations, and/or improvements of those features and/or examples may bepossible. Accordingly, the examples, as set forth above, are intended tobe illustrative. Various changes may be made without departing from thebroad spirit and scope of the underlying principles.

For example, in step 1251, if the first link La is not adjacent to thesecond link Lb in the map data, but the first link La is adjacent to thethird link Lc (e.g., there is an incorrect link number between twoadjacent links), part of the second link numbers Nb that are close tothe first link La may be replaced with the first link number Na and theremaining second link numbers Nb may be replaced with the third linknumber Nc.

In this manner, for example in FIG. 9(a), if odd number of second linknumbers Nb exist in one group, the middle link number in the group (thatcorresponds to the travel time 10:00:03) may be replaced with the firstlink number Na.

In step 1262, if the first link La and the second link Lb or the firstlink La and the third link Lc are not adjacent in the map data, a commonlink Lab that is adjacent to both of the first link La and the secondlink Lb exists, and if more than one travel history data including thefirst link number Na exist, the link number for the common link Lab maybe replaced with the link number at the last travel time for the firstlink La. For example, as shown in FIGS. 10(a) and 10(b), if a necessarylink number “2” for a common link Lab is missing between the first linknumber “1” and the second link number “3”, the link number “1” for thelast travel time of the first link, may be changed to “2.”

In step 1264, if the first link La and the second link Lb are notadjacent, the first link La and the third link Lc are not adjacent, acommon link Lab which is adjacent to both of the first link La and thesecond link Lb exists, and if only one travel history data including thefirst link number Na exists, a link number that appears before the firstlink number with a plurality of travel history data may be referencedand used to assign the missing link numbers.

For example, as shown in FIGS. 11(a) and 11(b), a necessary link number“4” for a common link Lab is missing between the first link number “3”and the second link number “5,” and there is only one travel historydata for the first link “3” (i.e., 10:00:03). The link which appearsbefore the first link and which has more than one travel history data,may have the link number for the last travel history data increased, andthe first link adjusted accordingly. Thus, as shown in FIGS. 11(a) and11(b), the link number “1” is the first link that appears before thefirst link number “3” having more than one travel history data, 10:00:01and 10:00:02. The last travel history data is for link number “1” isincreased to link number “2” and the remaining links “2” and the firstlink “3” are each increased by one accordingly.

In step 1271, if the first link La and the second link Lb are notadjacent or the first link La and the third link Lc are not adjacent, ifthere is no common link Lab which is adjacent to both of the first linkLa and the second link Lb, and if a common link Lac which is adjacent toboth of the first link La and the third link Lc is found (i.e., anecessary link number allocated for a common link Lac is missing betweenthe first link number Na and the third link number Nc and an incorrectlink number exists instead) the second link number Nb may be replacedwith the link number allocated for the common link Lac

For example, as shown in FIG. 12(a), if a first link number “1” and asecond link number “98” are not adjacent, a first link number “1” and athird link number “3” are not adjacent, and a common link number “2” isfound which is adjacent to both the first and third link, the secondlink number “98” may be replaced with the common link number “2.”Accordingly, as shown in FIG. 12(b) the non-adjacent link number “98”may be replaced with the adjacent link number “2” and each of the firstlink “1,” the replaced second link “2,” and the third link “3” will becorrectly adjacent and in order.

The above-described travel history data correction apparatus 101,comprises a controller that stores vehicle travel data taken in the pastas travel history data associated with a plurality of link numbers,detects adjacency relationships among the plurality of link numbers(e.g., steps 1240, 1250), and replaces a link number allocated for alink which has no relationship with adjacent links with at least onelink number allocated for a link which has a relationship with adjacentlinks based on the detection by the controller (e.g., steps 1251, 1262,1264, 1271).

By replacing link numbers, an incorrect link number allocated for a linkwhich has no relationship with adjacent links may be accuratelycorrected with at least one link number allocated for a link which has arelationship with adjacent links. Therefore, after the correction, areliable route may be searched and traffic information may be correctlydisplayed with using the dependable travel history data.

Further, the travel history data correction apparatus 101 comprises acontroller 113 that detects a current position (via current positiondetection unit 111). The controller 113 may store a link numbercorresponding to the current position as travel history data.

The travel history data correction apparatus 101 comprises thecontroller 113 that may store vehicle travel data taken in the past astravel history data associated with a plurality of link numbers as wellas times to pass through the links, and then the controller 113 may, ifthere is a link which has no relationship with adjacent links, replacethe link number with at least one link number allocated for a link whichhas a relationship with adjacent links based on a time to pass throughthe link.

The travel history data correction apparatus 101, comprises thecontroller 113 that stores vehicle travel data taken in the past astravel history data associated with a plurality of link numbers, forexample in memory 114, determines whether there a first link La that isallocated a first link number Na is adjacent to and a second link Lbthat chronologically appears after the first link number and that isallocated at least one second link number Nb. (e.g., step 1240). Thecontroller 113 determines from the travel history data whether there isthe first link La is adjacent to a third link Lc that chronologicallyappears after the second link number and which is allocated a third linknumber (Nc) (e.g., step 1250). If the controller 113 detects that thefirst link La and the third link Lc, the controller 113 replaces thesecond link number with at least one first link number and/or third linknumber (e.g., step 1251).

By replacing the link numbers, an incorrect link number allocated for alink which has no relationship with adjacent links may be accuratelycorrected with at least one previous and/or following link number.Therefore, a reliable route may be searched and traffic information maybe correctly displayed with using the dependable travel history data.

The controller 113 detects whether the first link La and the third linkLc are adjacent. The controller 113 detects whether there is a firstcommon link Lab which connects with both of the first link La and thesecond link Lb (e.g., step 1260), and replaces a link number at a lasttime for the first link La with a link number allocated for the firstcommon link Lab if the first link La is not adjacent to the second linkLb, the second link is not adjacent to the third link Lc, and if thefirst common link is detected (e.g., steps 1262, 1264).

By replacing link numbers, even if a link number is missing, a linknumber allocated for a common link may be appropriately used.

The travel history data correction apparatus 101 includes a controller113 that detects whether there is only one travel history data includingthe first link number, stores vehicle travel history as travel historydata in relationship to a plurality of link numbers and travel times. Ifa first link La and a second link Lb are not adjacent, the first link Laand a third link Lc are not adjacent, a common link Lab which isadjacent to both of the first link La and the second link Lb exists, andonly one travel history data including the first link number Na exists,the controller 113 may reference a link number that appears before thefirst link number and has a plurality of travel times (travel historydata), to assign missing link numbers.

For example, as shown in FIGS. 11(a) and 11(b), a necessary link number“4” for a common link Lab is missing between the first link number “3”and the second link number “5,” and there is only one travel historydata for the first link “3” (i.e., 10:00:03). The controller mayincrease the link number for the last travel history data of a linkwhich appears before the first link and which has more than one travelhistory data, and may adjust the following link numbers accordingly.Thus, as shown in FIGS. 11(a) and 11(b), the link number “1” is thefirst link that appears before the first link number “3” having morethan one travel history data, 10:00:01 and 10:00:02. The last travelhistory data is for link number “1” is increased to link number “2” andthe remaining links “2” and the first link “3” are each increased by oneaccordingly.

By executing such replacing processing, even if a link number ismissing, a link number adjacent to the missing link number may beappropriately used.

The travel history data correction apparatus 101, including controller113 detects whether the first link La and the third link Lc areadjacent, detects whether there is a first common link Lab that connectsboth of the first link La and the second link Lb, and detects whetherthere is a second common link Lac which connects with both of the firstlink La and the third link Lc (e.g., step 1270). The controller 113replaces a link number for the second link Lb with a link numberallocated for the second common link Lac (e.g., step 1271), when thefirst link La and the third link Lc are not adjacent and there is not afirst common link Lab that connects both of the first link La and thesecond link Lb, and a common link Lac is found.

By replacing link numbers, an incorrect link number allocated for a linkwhich has no relationship with adjacent links may be accuratelycorrected with a link number allocated for a link adjacent to the linkin question.

If there is a link which has no relationship with adjacent links, thelink number may be replaced with at least one link number allocated fora link which has a relationship with adjacent links in view of adjacencyrelationships among the plurality of link numbers.

By executing such replacing processing, an incorrect link numberallocated for a link which has no relationship with adjacent links maybe accurately corrected with at least one link number allocated for alink which has a relationship with adjacent links.

When vehicle travel data taken in the past is stored as travel historydata associated with a plurality of link numbers, the first link Laincluding the first link number Na is not adjacent to the second link Lbincluding at least one second link number Nb which appears right afterthe first link number, it may be determined whether the first link La isadjacent to the third link Lc including the third link number Nc. Thesecond link number Nb may then be replaced with at least one first linknumber Na and/or at least one third link number Nc in the travel historydata.

By replacing link numbers, an incorrect link number allocated for a linkwhich has no relationship with adjacent links may be accuratelycorrected with at least one previous and/or following link number.

Note that, for ease of explanation, the above-described apparatus andmethods are described with the aid of reference numerals. It should beappreciated that the respective structure and method steps representedby the reference numerals are merely exemplary.

While various features have been described in conjunction with theexamples outlined above, various alternatives, modifications,variations, and/or improvements of those features and/or examples may bepossible. Accordingly, the examples, as set forth above, are intended tobe illustrative. Various changes may be made without departing from thebroad spirit and scope of the underlying principles.

1. A navigation apparatus, comprising: a controller that: stores aplurality of types of past traffic information, each type of pasttraffic information having a priority; and merges the stored pasttraffic information in accordance with the priorities.
 2. The apparatusof claim 1, wherein the controller: receives current trafficinformation; and merges the current traffic information with the storedpast traffic information.
 3. The apparatus of claim 2, wherein thecontroller: calculates, for each type of stored past trafficinformation, a time difference between a travel time of the stored pasttraffic information and a travel time of the current trafficinformation; and sets the priority for each type of the stored pasttraffic information based on the calculated time difference;
 4. Theapparatus of claim 1, wherein the controller merges the stored pasttraffic information by overwriting low-priority stored past trafficinformation with high-priority stored past traffic information.
 5. Theapparatus of claim 2, wherein: the controller merges the stored pasttraffic information by weighted averaging low-priority stored pasttraffic information with high-priority stored past traffic information,the high-priority stored past traffic information having a higher weightthan the low-priority stored past traffic information.
 6. A apparatus ofclaim 5, wherein: the weight for each type of the stored past trafficinformation is determined by multiplying the stored past trafficinformation by a specified ratio, prior to calculating the average; andeach specified ratio is set for the corresponding type of past trafficinformation according to the priorities.
 7. The apparatus of claim 1,wherein the controller merges the stored past traffic information foreach of a plurality of predetermined areas.
 8. The apparatus of claim 1,wherein the controller sets the priority for each type of stored pasttraffic information for each of a plurality of predetermined timeperiods.
 9. A navigation method, comprising: storing a plurality oftypes of past traffic information, each type of past traffic informationhaving a priority; and merging the stored past traffic information inaccordance the with priorities.
 10. The method of claim 9, furthercomprising: receiving current traffic information; wherein merging thestored past traffic information comprises merging the current trafficinformation with the stored past traffic information.
 11. The method ofclaim 10, further comprising: calculating, for each type of stored pasttraffic information, a time difference between a travel time of thestored past traffic information and a travel time of the current trafficinformation; and setting the priority for each type of the stored pasttraffic information based on the calculated time difference;
 12. Themethod of claim 9, wherein merging the stored past traffic informationcomprises merging the stored past traffic information by overwritinglow-priority stored past traffic information with high-priority storedpast traffic information.
 13. The method of claim 10, wherein: mergingthe stored past traffic information comprises merging the stored pasttraffic information by weighted averaging low-priority stored pasttraffic information with high-priority stored past traffic information,the high-priority stored past traffic information having a higher weightthan the low-priority stored past traffic information.
 14. A method ofclaim 13, further comprising: determining the weight for each type ofthe stored past traffic information is by multiplying the stored pasttraffic information by a specified ratio, prior to calculating theaverage; and setting each specified ratio for the corresponding type ofpast traffic information according to the priorities.
 15. The method ofclaim 9, wherein merging the stored past traffic information comprisesmerging the stored past traffic information for each of a plurality ofpredetermined areas.
 16. The method of claim 9, further comprising:setting the priority for each type of stored past traffic informationfor each of a plurality of predetermined time periods.
 17. A storagemedium storing a set of program instructions executable on a dataprocessing device and useable to implement the method of claim
 9. 18. Anavigation apparatus that corrects traffic information data, the trafficinformation data including travel history data for a plurality of links,the apparatus comprising: a controller that: detects adjacencyrelationships among the plurality of links; and if a detected linknumber indicates that the corresponding link is not adjacent to adjacentlinks, replaces the detected link number for the link, the replaced linknumber indicating that the link is adjacent to the adjacent links.
 19. Anavigation method for correcting traffic information data, the trafficinformation data including travel history data for a plurality of links,the method comprising: detecting adjacency relationships among theplurality of links; and replacing, if a detected link number indicatesthat the corresponding link is not adjacent to adjacent links, thedetected link number for the link, the replaced link number indicatingthat the link is adjacent to the adjacent links.
 20. A storage mediumstoring a set of program instructions executable on a data processingdevice and usable to implement the method of claim 19.